Last season, the St. Louis Rams offense failed to do much of anything. Trying to pinpoint a reason for those struggles is as elusive as a Rams touchdown. Injuries to key players, a general lack of experience and battered quarterback syndrome all share some blame. That last factor, poor QB play, is something I keep coming back to as 20/20 hindsight brings the 2009 season into a little better focus.
Let's take a look at QB play through a statistical lens using the stats from Advanced NFL stats. What it reveals is a Rams offense that suffered for a number of factors, but QB play was a central culprit in the offensive struggles.
What you see above are two QBs who took more away from the team's offense than they added to it.
A quick review of the stats used and the numbers presented. Win Probability Added (WPA) gauges the weighted impact of each play the QB was involved in, be it to a lesser extent like a hand-off or a more direct responsibility like an interception. Estimated Points Added (EPA) is similar, quantifying a player's contribution in terms of points. Success Rate (SR) is defined as "percent of plays in which the player participated that result in an increase in net expected point advantage." SR is all about consistency.
As you can see, Marc Bulger and Kyle Boller didn't have a very positive impact on the Rams offense. Boller cost the Rams quite a bit more in the seven games where he saw action (four starts) than did the Bulger in his nine games played (eight starts). No surprise to anyone who lost a good portion of their lives watching those games. Each QB threw six interceptions and Boller was sacked three more times than Bulger, 17 to 14. Those cost Boller quite a bit more in terms of WPA and EPA since he played less, to state the obvious.
You'll notice that the success rate of the two QBs is pretty close, roughly 4 percentage points separating them. Consistency-wise, Bulger may have been the Rams better QB, but not by much. Obviously, those numbers are impacted by the team around them (more on that below), but because these numbers account for the relative value of each play, they do reveal plenty about Boller and Bulger's ability to make things happen.
Numbers aren't available for Keith Null.
Going by EPA, Boller and Bulger cost the Rams 72 points. Add that to the 175 points the Rams scored in 2009 and their average per game goes from 10.9 to 15.4. The Rams would have still likely been the worst in the division with those 72 extra points, but there were enough close games that a point or two here and there could have made for a slightly better record...and a coin flip for the first overall pick.
Two things to consider in Bulger's numbers versus Boller. First, Bulger got better offensive line play which helped his sack rate quite a bit compared to his backup's. Stronger play up front is also revealed in Steven Jackson's rushing totals for the games Bulger played. Jackson had six games with 100+ yards rushing in the 9 games Bulger played; the Green Bay game is a little problematic since Bulger left after just 4 throws. Still, six of Jackson's 100+ yard games happened when Bulger was under center. Those two factors certainly helped his EPA. With a mediocre running back and the offensive lines he was used to playing behind, Bulger might have had a much uglier number.
I don't want to oversell you on the simplicity of the stats. Like I said above and like we've noted for a long time, the Rams offense was bad on several levels. Nevertheless, it does reveal that QB play was a pretty significant weakness for the Rams last season and a major need to be addressed before opening the doors on 2010 come September.
Now, the question becomes what can Sam Bradford, the first overall pick in this year's draft, do for the Rams?